This application claims the priority of German application 198 48 744.4, filed Oct. 22, 1998, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a brazed condenser for an air conditioner, such as a motor vehicle air conditioner, having a block of tubes and fins arranged between two collecting tubes, and with a tube-shaped collector which is mounted laterally on one of the collecting tubes.
In one such condenser known from U.S. Pat. 5,159,821, the condenser is assembled and then brazed in a furnace. In order to hold the parts of the condenser together, particularly the collecting tube formed of two half shells, and also to connect this collecting tube with the tube-shaped collector, molds must be provided to hold the condenser in the preassembled condition until the condenser is brazed.
It is also known from German Patent Document DE 195 36 999 A1 to hold the two-part collecting tube together with a collector molded of a plane steel sheet bar, as a result of a plastic deformation of elements, such that they can be brazed to one another in a furnace.
It is also known from European Patent Documents EP 689 014 A1 and EP 0 669 506 A1 to provide an extruded tube as a collector which is provided on the outside with profile strips extending in the longitudinal direction and forming a collecting tube together with a half shell. These elements are also joined into a preassembly and are then brazed in a furnace. Joining must take place very carefully, while handling of the condenser during transport to the brazing furnace must also be carried out very carefully so that the parts do not slide with respect to one another; this could impair tight soldering.
It is an object of the invention to simplify a condenser of the initially mentioned type, particularly with respect to the design of the collecting tube and the collector, and to ensure that these parts are also securely connected with one another before brazing in a brazing furnace.
This object is achieved by prefabricating the collecting tube as a one-piece tube which is connected with the collector by tack weld seams.
The use of a one-piece collecting tube is advantageous since the tube already has its final shape so that no parts can be displaced with respect to one another. Furthermore, tack weld seams can be made in a simple manner between the one-piece collecting tube and the collector and provide sufficient stability until final brazing-together.
In an advantageous further development of the invention, the tack weld seams are constructed as laser weld seams. Such laser weld seams have the advantage that the introduction of heat into the collector and into the collecting tube is relatively low so that thermal deformations which may impair subsequent tight brazing are not to be expected.
In a further development of the invention, at least one of the tubes is provided with a plastic deformation for forming a contact surface for the other tube. In an advantageous further development, at least one connection opening between the two tubes is provided in the area of the deformation. Flat contact in the area of the plastic deformation ensures that the area of the connection openings is reliably tightly brazed toward the outside.
In a first embodiment of the invention, the tube of the collector is extended by a coaxial tube piece which is provided on the outside with a longitudinal groove forming a contact surface for the collecting tube. The use of such a coaxial tube piece permits the provision of a secure contact surface. In a further development, the coaxial tube piece is provided with an internal thread for receiving a plug. The coaxial tube piece, therefore, also functions to make a sufficient wall thickness available for providing an internal thread for a plug.